English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Plus annual

Presents the access of premium content as premium feature

Premium Content

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Tools annual

Global: Zendy Free Plan

Global: Zendy Tools monthly

Global: Zendy Plus monthly

A push-pull olefin, E-2, was prepared highly stereoselectively by reaction of ethyl (2- cyanoacetyl)carbamate, 1, with ethyl orthoformate in the presence of acetic anhydride. Forty percent of E-2 was isomerized to Z-2 after two hours of irradiation at 254 nm. All the Z-2 was isomerized back to E-2 spontaneously and irreversibly with Ea = 19.6 kcal mol -1 , ∆H ‡ = 19.0 kcal mol -1 , ∆S ‡ = -17.5 cal K -1 mol -1 , and ∆G ‡ = 24.4 kcal mol -1 . The negative entropy of activation for this isomerization indicates that the transition state has much more charge separation than the ground state. The low rotational barrier of this isomerization and very big chemical shift difference (∆δC=C = 85.83 ppm) of two sp 2 -hybridized carbons of C=C partial double bond confirm 2 is a push-pull olefin.

Ethyl (2-cyano-3-ethoxyacryloyl)carbamate: irreversibly thermal isomerization of a push-pull olefin